Vera M Kolb And Patrick J Liesch
Department of Chemistry, University of Wisconsin-Parkside, Kenosha, WI53141-2000, USA Abstract Silicates are abundant on both Earth and Mars, and hold great potential for harboring biosignatures. Biosignatures are signs of past or present life and may be either organic or inorganic in nature. Our most recent work, which we review here, is a survey of how different classes of organic compounds interact with highly basic sodium silicate solution to model the formation of biosignatures in nature....
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J. Seckbach and M. Walsh eds. , From Fossils to Astrobiology, 3-23. Springer Science Business Media B. V. 2009 Biodata of Smail Mostefaoui, co-author with Dorothy Z. Oehler, Fran ois Robert, Anders Meibom, Madeleine Selo, David S. McKay, and Everett K. Gibson . Dr. Smail Mostefaoui is a research engineer and NanoSIMS specialist at LEME Laboratoire d'Etude de la Mati re Extraterrestre at the Mus um Nationale d'Histoire Naturelle in Paris. He obtained his Ph.D. at the Mus um in 1996 in isotopic...
Vinod Chandra Tewari
Wadia Institute of Himalayan Geology, Dehra Dun 248 001, Uttarakhand, India and International Centre for Theoretical Physics, Miramare 34100 Trieste, Italy A comparative study of possible genesis of life on planet Earth and Mars reveals that similar conditions would have been present on Mars supporting a probable occurrence of unicellular Martian microfossils and stromatolites. The genetic aspect of eukaryotes or eukaryogenesis, eukaryotic evolution and probable geological and recent...
Shuhai Xiao And James D Schiffbauer
Department of Geosciences, Virginia Polytechnic Institute and State University, Blacksburg, Virginia 24061, USA One of the major tasks of astrobiology is to critically examine evidence of past or present ecosystems beyond our planet. As Earth is the only planet that is known to have hosted life, perhaps as early as 3.8-3.5 billion years ago or Ga, Giga anna as illustrated by biologically-meaningful carbon isotopic signatures and prokaryotic microfossils Mojzsis et al., 1996 Schopf, 2006 but see...
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Dr. David S. McKay Dr. Everett K. Gibson NANOSIMS OPENS A NEW WINDOW FOR DECIPHERING ORGANIC MATTER IN TERRESTRIAL AND EXTRATERRESTRIAL SAMPLES DOROTHY Z. OEHLER1, FRAN OIS ROBERT2, SMAIL MOSTEFAOUI2, ANDERS MEIBOM2, MADELEINE SELO2, DAVID S. MCKAY1 AND EVERETT K. GIBSON1 'Astromaterials Research and Exploration Science Directorate, NASA-Johnson Space Center, Houston, Texas 2Laboratoire d'Etude de la Mati re Extraterrestre, Mus um National d'Histoire Naturelle, Paris, France Recognition of the...
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This sponge may be called as mermaid globe or dead man fingers as it is palm shaped with several fingers perforated with oscula. The skeleton of the present specimens apparently made of spongin fibers. Siliceous spicules are not visible. These specimens also show radial symmetry and Leuconoid type canal system as its body is massive and shows numerous flagellated chambers. The present form is morphologically comparable with the known extant genera, Chalina. Though, the general morphology of the...
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Figure 1. Schematic summary of preservation resolution, temporal distribution, and environmental distribution of various taphonomic pathways Butterfield, 2003 . lack of phosphatization of more labile substrates such as cellular and subcellular structures. Some phosphatized biotas in Cambrian successions Zhang and Pratt, 1994 Bengtson and Yue, 1997 Dong et al., 2004 may be considered as transitional taphonomic windows that bridge the end members of the Doushantuo and Orsten biotas, because they...
Evolution And Astrobiology
Paleontological Tests Human-Like Intelligence Is Not a Convergent Feature of Evolution Lineweaver, C.H. 353 Cosmic Life Forms Grandpierre, ASTRONOMIcAL AND cOSMOLOGIcAL cONSIDERATIONS IN ASTROBIOLOGY Astronomical and Astrobiological Imprints on the Fossil Records A Review Chela-Flores, J. et Do Impacts Really Cause Most Mass Extinctions Prothero, Irradiation of Icy Cometary Analogs Its Relevance in Reference to Chemical Evolution and the Origin of Life Colin-Garcia, M. et al. The Big Bang at...
32 Pilbara Microfossils
Perhaps the most well known report of microfossil evidence for earliest life comes from the 3,460 Ma 'Apex chert'. These Apex 'microfossils' e.g., Fig. 2f were described in detail in a series of high profile papers Schopf and Packer, 1987 Schopf, 1992a, b, 1993 Schopf et al., 2002 and became the benchmark for bona fide early Archean 'microfossils', the only ones to gain wide acceptance by the scientific community during the 1980s and 1990s e.g., Buick, 1990 Knoll and Walter, 1996 McClendon,...
43 Barberton Sulfur Isotopes
A similar sulfur isotope story to that in the Pilbara emerges in the Barberton area from the work of Ohmoto et al. 1993 . These authors sampled a shale and three black cherts from the uppermost Onverwacht Group 3,300 Ma Mendon Formation in the Barberton and used high resolution laser ablation mass spectroscopy to analyse individual pyrite grains. The range of 534S values up to 12 o variation from these pyrites was argued to be greater than that expected if they had formed from purely magmatic...
Foreword
From Fossils to Astrobiology Records of Life on Earth and Search for Extraterrestrial Biosignatures Astrobiology, the study of life in the universe, draws on many traditional areas of scientific study, including astronomy, chemistry and planetary science. This volume, number 12 in the Cellular Origin, Life in Extreme Habitats and Astrobiology series published by Springer focuses on the study of the record of life on planet Earth, which is critical in guiding investigations in the rest of the...
Wladyslaw Altermann
Department of Earth- and Environmental Sciences, Ludwig-Maximilians-University amp GeoBioCenterLMU, Luisenstr. 37, D-80333 Munich, Germany Joseph Seckbach, the editor of the present book series, invited me to write the introduction to From Fossils to Astrobiology during his 3 months visit to my Institute at the Ludwig-Maximilians-University under the fellowship of DAAD German Academic Exchange Foundation in 2006. Of course I felt honoured by his choice, but being sceptical towards the youngest...
Ho
Figure 1. Polymerization of silicic acid. Figure 2. An example of organo-silicate ribose bottom left , serine bottom right , and threonine top right , make Si-O-C bonds with silicic acid within the silica gel. Figure 2. An example of organo-silicate ribose bottom left , serine bottom right , and threonine top right , make Si-O-C bonds with silicic acid within the silica gel. of silicic acid to silica gel. Silica gel is characterized by the presence of the Si-O-Si bonds and Si-OH groups. Organic...
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Tyler, S.T. and Barghoorn, E.S. 1963 . Ambient pyrite grains in Precambrian cherts. Am. J. Sci. 261, 424-432. Ueno, Y., Isozaki, Y., Yurimoto, H. and Maruyama, S. 2001 . Carbon isotopic signatures of individual Archean microfossils from Western Australia. Int. Geol. Rev. 43, 196-212. Ueno, Y., Yurimoto, H., Yoshioka, H., Komiya, T. and Maruyama, S. 2002 . Ion microprobe analysis of graphite from ca. 3.8 Ga metasediments, Isua supracrustal belt, West Greenland relationship between metamorphism...
41 Barberton Microtubes
The most ancient structures described from the Onverwacht Group are mineralized microtubes from the formerly glassy margins of pillow basalts and inter-pillow - gt Figure 3. continued Research, Volume 106. Westall, F. de Witt, M.J., Dann, J., van der Gaast, S., de Ronde, and Gerneke, D. Early Archean fossil bacteria and biofilms in hydrothermally-influenced sediments from the Barberton greenstone belt, South Africa, pp. 93-116. Copyright 2001 , with permission from Elsevier. Figure 3d and f are...
33 Pilbara Microtubes
Remarkably preserved microtubular structures have recently been reported from a silicified sandstone unit at the base of the 3,400 Ma Strelley Pool Chert Wacey et al., 2008a Brasier et al., 2006 . Ongoing investigations of these structures show several lines of evidence consistent with a biogenic interpretation. The geological context of the sandstone unit appears conducive for life. This is evidenced by the presence of low angle cross bedding, channels and relatively high textural and...
Isua Greenstone Belt
J. Seckbach and M. Walsh eds. , From Fossils to Astrobiology, 25-37. Springer Science Business Media B. V. 2009 DISENTANGLING THE MICROBIAL FOSSIL RECORD IN THE BARBERTON GREENSTONE BELT A CAUTIONARY TALE 1School of Plant, Environmental, and Soil Sciences, Louisiana State University, Baton Rouge, Louisiana 70803, USA 2Centre de Biophysique Mol culaire, Centre National de la Recherche Scientifique, 45071 Orl ans cedex France Abstract Morphological remains of microbes are one of several lines of...
31 Pilbara Stromatoloids
Stromatolites are laminated sedimentary structures that provide a controversial candidate signature for early life. In the following discussion, we therefore adopt the non-genetic term 'stromatoloid', thus making no assumptions about their biogenicity cf. Buick et al., 1981 . A stromatoloid can be defined non-genetically as an attached, laminated, lithified sedimentary growth structure, accretionary away from a point or limited surface of initiation Semikhatov et al., 1979 , and in outcrop are...